Yes, very simple for people, very difficult for “machinery”. Don > On Jun 21, 2016, at 7:01 PM, William H. Fite <omni...@gmail.com> wrote: > > In the days of my misspent youth, I worked as a telegrapher (one of the > very last) for a Norwegian shipping line. We sent and received both > Norwegian and English though few of us were bilingual. Between ships and > shore stations, there were about forty of us and we all could recognize > each other's "fists" with near-perfect accuracy. This is not difficult, > gentlemen, and does not require any esoteric signal analysis. Transmitters > would be a different story. > > Bill KJ4SLP > > > > On Tuesday, June 21, 2016, John Ackermann N8UR <j...@febo.com > <mailto:j...@febo.com>> wrote: > >> I've seen references that at least by the latter part of WW2 oscillographs >> were being used to identify transmitters and/or ops. It should be possible >> to deduce chirp, rise time, fall time of signals, all of which characterize >> the transmitter, as well as element spacing and other characteristics that >> help identify the operator, from oscilloscope snapshots of the demodulated >> audio at various sweep speeds. >> >> >>> On Jun 21, 2016, at 7:02 PM, Alan Melia <alan.me...@btinternet.com >> <javascript:;>> wrote: >>> >>> TX "fingerprinting" in WWII >>> You seem to be forgetting that there were very few of the sophisticated >> digital timing systems were available 75 years ago. Traffic analysis was >> started early in 1938 or even before. By 1939 we knew all the nets used in >> Europe and had "Y" ( a corruption of WI, Wireless Intercept )operators >> monitoring the nets. Many of these were amateurs and they were allocated to >> specific nets and followed them around as they moved. They became very >> familiar with the "accents" of operators on their nets, and particularly >> before 1939 security procedures were very lax and "chatting" >> common-place.....but it was all aural. >>> >>> I suspect serious transmitter parameter logging was not done before the >> cold war when spectrum analysers, or at least pan-adapters became more >> readily available. To keep a little OnTopic .....you would have difficulty >> doing this with a BC-221.!! :-)) A crystal clock of this period was at >> least one fully utilised 6foot 19inch rack (there is one at Grenwich.) >>> Alan >>> G3NYK >>> >>> >>> Alan >>> G3NYK >>> >>> ----- Original Message ----- From: "jimlux" <jim...@earthlink.net >> <javascript:;>> >>> To: <time-nuts@febo.com <javascript:;>> >>> Sent: Tuesday, June 21, 2016 10:02 PM >>> Subject: Re: [time-nuts] Measuring receiver... >>> >>> >>>>> On 6/21/16 11:28 AM, Brooke Clarke wrote: >>>>> Hi: >>>>> >>>>> During W.W.II there were secret methods of "fingerprinting" radio >>>>> transmitters and separately the operators. >>>>> I suspect the transmitter fingerprinting involved things like frequency >>>>> accuracy, stability, CW rise and decay time, &Etc. For the operator >> some >>>>> from of statistics on the timings associated with sending Morse Code. >>>>> But. . . I haven't seen any papers describing this. Can anyone point >>>>> me to a paper on this? >>>> For "human controlled" stuff, e.g. recognizing someone's "fist", >> there's a huge literature out there on biometric identification looking at >> things like keyboard and mouse click timing - the timing requirements are >> pretty slack, and hardly time-nuts level, unless you're looking to do it >> with mechanical devices constructed from spare twigs and strands of kelp. >>>> >>>> There have been a variety of schemes for recognizing individual radios >> by looking at the frequency vs time as they start up. Likewise, it's pretty >> easy to distinguish radar magnetrons from each other. Not a lot of papers >> about this, but you'll see it in advertising literature, or occasionally in >> conference pubs (although I can't think of any off hand). There was >> someone selling a repeater access control system that was based on the >> transmitter fingerprint. >>>> >>>> But the real reason why you don't see any publications is that this >> stuff is pretty classic signals intelligence (SIGINT or MASINT) and it is >> still being used, and is all classified. You're not relying on Betty the >> receiver operator to recognize the characteristic chirp as the agent's >> radio is keyed, it's all done by computer now, but the basic idea is the >> same. And as with most of this stuff, the basics are well known, but the >> practical details are not, or, at least, are the proprietary secret sauce >> in any practical system. (In a significant understatement, Dixon, in >> "Spread Spectrum Systems" makes some comment about how synch acquisition is >> the difficult part and won't be described in the book) >>>> >>>> You might look at the unclassified proceedings of conferences like >> MILCOM and find something. Googling with MASINT might also help. >>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- time-nuts@febo.com <javascript:;> >>>> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- time-nuts@febo.com <javascript:;> >>> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com <javascript:;> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > -- > I am Pulse. Unbreakable. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com <mailto:time-nuts@febo.com> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > and follow the instructions there.
Felix qui potuit rerum cognoscere causas. Lucky is he who has been able to understand the causes of things. Virgil ------------------------------- "Noli sinere nothos te opprimere" Dr. Don Latham, AJ7LL Six Mile Systems LLC, 17850 Six Mile Road Huson, MT, 59846 mailing address: POBox 404 Frenchtown MT 59834-0404 VOX 406-626-4304 CEL 406-241-5093 Skype: buffler2 www.lightningforensics.com <http://www.lightningforensics.com/> www.sixmilesystems.com <http://www.sixmilesystems.com/> _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.